Method of making a plated article



May 29, 1962 R. R. KAPSH ET AL METHOD OF MAKING A PLATED ARTICLE Filed June 17, 1959 INVENTORS RALPH R. KAPSH and WILLIAM S. VAG'LI United tates 3,036,376 METHOD OF MAKING A PLATED ARTKZLE Ralph R. Kapsh, Pittsburgh, and William S. Vagli, Moniessen, Pa, assignors to United States Steel Corporation, a corporation of New Jersey Filed June 17, 1959, Ser. No. 820,892 2 Claims. (Ci. 29-527) This invention relates to a method of making a plated article and more particularly to a method of making an automobile bumper. In making an automobile bumper a steel slab is hot rolled substantially to the desired gauge and coiled. Subsequently the coiled strip is uncoiled. During the coiling, cooling and uncoiling operations contraction marks or scratches are caused by scraping of the strip convolutions. These surface imperfections are particularly serious on bumper stock since the subsequent forming and plating operations highlight the surface defects and cause rejection of the finished article. In fact, the number of rejects were so high (generally between 15 and 20%) that serious consideration was given to cold rolling the hot rolled strip to improve its surface finish. This would, of course, add substantially to the cost thereof.

It is therefore an object of our invention to provide a method of making hot rolled steel strip which is relatively free of surface defects.

Another object is to provide a method of making a plated article.

These and other objects will be more apparent after referring to the following specification and attached drawings, in which:

The single FIGURE is a schematic view of the steps performed in a preferred method of carrying out our invention.

Referring more particularly to the drawings reference numerals '2, 4, 6, 8 and 10 indicate the rolls of a tandem hot rolling mill for producing strip S which is coiled on a reel 12. While five roll stands are shown, more stands are commonly used with the slab being gradually reduced in thickness as it passes therethrough.

We have found that by using roughened work rolls 14 in at least the last stand 10 a flaked scale is provided on the hot rolled strip S. This flaked scale, which is powdery in appearance, acts as a lubricant between the convolutions of the coil of strip duiing the hot mill coiling operations, cooling and storage, and uncoiling for subsequent processing steps. The roll 14 is preferably ground by shot blasting in a conventional centrifugal blasting unit using classified chilled iron grit between sizes 50 and 80. The roll travels beneath the centrifugal impeller at difierent rates for ditferent types of finish. For example, for a so-called No. finish it will travel at a rate of 84" in 9 minutes, and for a No. 5A finish it will travel 84" in 12 minutes. For both finishes the roll is rotated at approximately 12 rpm. during the shot blasting operation. It is quite common to use roughened rolls on cold reduction and temper mills to obtain a rough surface on the finished products. However, the object of using such rolls and the finish obtained on the strip 3,036,376 Patented May 29, 1852 "ice are different than when hot rolling. The main difference is that the oxide formed during the hot rolling operation does not form during cold rolling operation. Our method has reduced the number of rejects to less than 5%.

In producing a bumper or other plated article it is necessary to remove the scale prior to the plating operation. Other steps may be desirable, but these two steps are essential in making any plated article. One manner of producing a bumper is shown in the drawings wherein a coil of strip S is uncoiled and passed through slitting rolls 16 and transverse shears 18 to form sheets SH of the desired size. The sheets SH are passed through a roller leveler 2t and are then piokled in the pickling tank 22 and passed through a roller leveler 24. At least one side of the sheet SH is then polished as by means of a belt grinder 26. The step is important when a highly polished chrome plate is to be obtained. The sheet SH is then shaped by means of a press 28 into the form of a bumper B. Bumper B is then electro-plated in tank 30. The plating may be performed in two steps with a base coating of copper or nickel being applied prior to coating with chromium.

While one embodiment of our invention has been shown and described it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

We claim:

1. The method of making a plated article which comprises providing a steel workpiece, heating the workpiece to its hot rolling temperature, then hot rolling the workpiece to strip in a tandem mill the last stand of which has work rolls with shallow depressions on the surface thereof so as to produce a flaked scale on the strip, coiling the strip with the flaked scale thereon, uncoiling the coiled strip with the flaked scale thereon, removing the oxide formed thereon during the hot rolling step, and then electro plating the strip.

2. The method of making an automobile bumper which comprises providing a steel workpiece, heating the workpiece to its hot rolling temperature, then hot rolling the workpiece to strip in a tandem mill the last stand of which has work rolls with shallow depressions on the surface thereof so as to produce a flaked scale on the strip, coiling the strip with the flaked scale thereon, uncoiling the coiled strip with the flaked scale thereon and removing the oxide formed thereon during the hot rolling step, shaping the strip into a plurality of bumpers, and then chrome plating the shaped bumpers.

References (lited in the file of this patent UNITED STATES PATENTS Re. 21,903 Brenneisen Sept. 23, 1941 479,780 Britton Aug. 2., 1892 1,490,944 Simpson Apr. 22, 1924 1,718,064- Naugle et a1. June 18, 1929 2,083,518 Lorig June 8, 1937 2,187,595 Wean Jan. 16, 1940 2,442,485 Cook June 1, 1948 2,650,888 Pottberg Sept. 1, 1953 

